1. Field of the Invention
The present invention is directed to an improved inkless fingerprint identification system, and more particularly, to a method and apparatus which permits the medium to directly receive in two segregated areas the proper thickness of liquid developer solution and liquid reagent solution so that a person can imprint his fingerprint by only contacting the medium.
2. Description of the Prior Art
Although there are other methods of identifying individuals, it has become readily apparent that fingerprints provide a unique and absolute means of identification that does not require cooperation from the subject. Fingerprint identification is an exacting science since two impressions of even the same fingerprint can appear different due to variations in inking, pressure, ink migration and changes in the finger itself with time. To determine an exact correspondence, a trained fingerprint technician will compare the pattern of ridge endings and ridge bifurcations (minutiae) which are invariant with time on each person's fingerprint. For a further discussion of the characteristics of fingerprint classification, reference is made to U.S. Pat. No. 3,419,287. The prior art has readily recognized that the key to any viable fingerprint identification system requires a clear distinct print pattern with a minimum of inking migration between associate ridges. An additional requirement for any voluntary print identification system, such as to be utilized commercially with checks and the like, is that it be inoffensive to the person whose fingerprint is being obtained. A prime offense to persons has been the necessity to utilize an ink that would stain the hands of the person, such as a fingerprint kit utilizing a pair of pads for applying ink and then removing the ink from the finger as disclosed in U.S. Pat. No. 3,318,282.
The prior art has directed a considerable amount of effort to try and develop a successful inkless fingerprinting system. One commercial approach has been to utilize a fine magnetizable powder that will adhere to the moisture of a fingerprint on a substrate surface, see U.S. Pat. No. 3,831,552.
U.S. Pat. No. 3,851,619 discloses an inkless fingerprinting system which includes an aerosol dispenser with a metering valve to control the dryness of a reagent solution at the point of impact on the print surface. The reagent solution having the solvent removed prior to the contact of the developer coated finger and the developer being a ferric salt, such as ferric chloride, with the respective materials being kept in an airtight enclosure. The problem with applying a developer solution to the ridge patterns of the fingerprint is recognized and purportedly solved by the use of a specific rigid pad with a spaced permeable membrane.
In applying the active materials of the reagent solution and the developer solution in an inkless printing system, there is a need to prevent, or minimize, migration or bleeding, not only with the initial contact of the fingerprint to the surface, but also over a period of time. Quite frequently, prints were developed that were acceptable for instantaneous recognition, but would deteriorate and limit the use of the print as a means of identification, for example, during a time period associated with clearing a check, or in the case of using the check as evidence in apprehending a forger. Conversely, other systems would permit a print to develop slowly over a period of time, but would not permit the print to be perceptible to an observer to determine if the print was immediately smudged, or blurred, at the time of taking the print.
Other approaches in the prior art can be found in the following patents: U.S. Pat. No. 2,082,735; U.S. Pat. No. 2,104,586; U.S. Pat. No. 2,198,802; U.S. Pat. No. 3,083,682; U.S. Pat. No. 3,258,277; U.S. Pat. No. 3,447,818; U.S. Pat. No. 3,694,240; and U.S. Pat. No. 3,584,958.
Commercially, various systems have been offered to the public, such as an ultra-violet ink pad, which permits the finger to contact the pad to apply the ink on the finger to a check. This system requires an ultra-violet light to determine if a good print has been taken.
Chemically impregnated stickers have also been provided for attachment to a document. A complementary chemically impregnated cardboard pad is provided for the finger to contact the cardboard pad, and then subsequently, contact the sticker to develop a fingerprint. Problems exist in both the quality of the fingerprint and in the removability of the sticker, for example, when using an automatic check reading machine.
Recently, the Federal Bureau of Investigation authorized a study on fingerprint ink, "The Influence of Ink on the Quality of Fingerprint Impressions" by R. T. Moore, NBSIR 74-627 (1974) and concluded that the thickness and uniformity of the ink film rolled on the glass plate is a major factor in producing impressions capable of being utilized with automatic fingerprint reading equipment. The study suggested that an ink film thickness of two micrometers was desirable and that the apparent viscosity of slipperiness of the ink was not as important as the volume of ink dispensed.
Apart from the field of fingerprinting, the paper industry has investigated the porosity of paper from both an empirical and theoretical approach, see "The Porous Structure of Paper", by H. F. Rance, Tenth Symposium of the Colston Research Society, Butterworth's Scientific Publication, London, Eng. (1958); "Capillary Penetration of Fibrous Materials", by R. L. Peck, Jr. et al, 1934, Industrial and Engineering Chemistry, Vol. 6, No. 2, page 85, and the Technical Association of the Pulp and Paper Industry standards, T 431-ts-65, T432-ts-64, T 433-m-44 and T 433-os-74. The information from the paper industry is simply provided as explanatory of the states of that art.
Many of the systems suggested in the prior art, suffer from the disadvantage of permitting an element of discretion to occur in the degree of coating of the finger by contact with an impregnated pad. If the chemical saturates the finger ridge pattern, a blurred print will occur. If an inadequate amount of material is applied to the finger ridge pattern, a fragmented fingerprint will be produced. An additional factor of sanitation in commercial establishments is also present when a large number of customers are forced to utilize the same pad.
There is a need in the prior art to provide a positive inkless fingerprinting identification system that isolates the person whose print is to be taken from the source of the reagents and developer chemical and also insures a quality recorded print. The prior art has failed to provide a controlled repeatable thickness of developer solution with an optimized integration of a reagent solution with the medium to insure a permanent clear print. Ideally, the system must be durable, convenient to the customer and not add any additional time to a purchase transaction involving a check. Also, the system must be capable of repeated use within a minimal cost.